Future development of amifostine as a radioprotectant

Animal data and clinical trials document the efficacy of amifostine (WR-2721, Ethyol; Alza Pharmaceuticals, Palo Alto, CA/US Bioscience, West Conshohocken, PA) in decreasing the effects of radiation on normal tissues without decreasing the cytotoxic effects on malignant tumors. The selection of the optimal dose may depend on the intensity of the regimen to be administered as well as on the normal tissues to be protected. Also of important consideration is the question of how to sequence amifostine infusion. The optimal amifostine schedule during the course of the combined-modality treatment may require shortening the duration of chemotherapy infusion or giving amifostine in two split doses (before and after chemotherapy). Wide application of amifostine in once-daily/multiple-daily fractionated radiotherapy regimens may be facilitated by the availability of other, nonintravenous delivery routes, which are being explored. Although efforts are currently directed at amifostine-mediated modification of acute or late mucosal reactions associated with radiation therapy, there are many other radiation-induced toxicities. Further randomized studies are necessary to document the effects of amifostine on nonmucosal damage. Amifostine has the potential to protect a broad range of normal tissues from the toxicities of radiation and from certain forms of chemotherapy.

Immediate side effects of stereotactic radiotherapy and radiosurgery

PURPOSE

Despite increased utilization of fractionated stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS), the incidence and nature of immediate side effects (ISE) associated with these treatment techniques are not well defined. We report immediate side effects from a series of 78 patients.

MATERIALS AND METHODS

Intracranial lesions in 78 adult patients were treated with SRT or SRS, using a dedicated linear accelerator. Those lesions included 13 gliomas, 2 ependymomas, 19 metastatic tumors, 15 meningiomas, 12 acoustic neuromas, 4 pituitary adenomas, 1 optic neuroma, 1 chondrosarcoma, and 11 arteriovenous malformations (AVM). SRT was used in 51 and SRS in 27 patients. Mean target volume was 9.0 cc. Eleven patients received prior external-beam radiation therapy within 2 months before SRT/SRS. Any side effects occurring during and up to 2 weeks after the course of radiation were defined as ISE and were graded as mild, moderate, or severe. The incidence of ISE and the significance of their association with several treatment and pretreatment variables were analyzed.

RESULTS

Overall, 28 (35%) of 78 patients experienced one or more ISE. Most of the ISE (87%) were mild, and consisted of nausea (in 5), dizziness/vertigo (in 5), seizures (in 6), and new persistent headaches (in 17). Two episodes of worsening neurological deficit and 2 of orbital pain were graded as moderate. Two patients experienced severe ISE, requiring hospitalization (1 seizure and 1 worsening neurological deficit). ISE in 6 cases prompted computerized tomography of the brain, which revealed increased perilesional edema in 3 cases. The incidence of ISE by diagnosis was as follows: 46% (6 of 13) for gliomas, 50% (6 of 12) for acoustic neuromas, 36% (4 of 11) for AVM, 33% (5 of 15) for meningiomas, and 21% (4 of 19) for metastases. A higher incidence of dizziness/vertigo (4 of 12 = 33%) was seen among acoustic neuroma patients than among other patients (p< 0.01). There was no significant association of dizziness/vertigo with either a higher average and maximum brainstem dose (p = 0.74 and 0.09, respectively) or with 2-Gy equivalents of the average and maximum brainstem doses (p = 0.28 and 0.09, respectively). Higher RT dose to the margin and higher maximum RT dose were associated with a higher incidence of ISE (p = 0.05 and 0.01, respectively). However, when RT dose to the margin was converted to a 2-Gy dose-equivalent, it lost its significance as predictor of ISE (p = 0.51). Recent conventional external-beam radiation therapy, target volume, number of isocenters, collimator size, dose inhomogeneity, prescription isodose, pretreatment edema, dose of prior radiation, fraction size (2.0-7.0 Gy with SRT and 13.0-21.0 Gy with SRS), fractionation schedule, and dose to brainstem were not significantly associated with ISE. ISE occurred in 26% (8) of 31 patients taking corticosteroids prior to SRT/SRS and in 20 (42%) of 47 patients not taking them (p = 0.15).

CONCLUSION

ISE occur in one third of patients treated with SRT and SRS and are usually mild or moderate and self-limited. Dizziness/vertigo are common and unique for patients with acoustic neuromas and are not associated with higher brainstem doses. We are unable to detect a relationship between ISE and higher margin or maximum RT doses. No specific conclusion can be drawn with regard to the effect of corticosteroids, used prior to SRS/SRT, on the occurrence of ISE.

A phase I dose escalation study of hypofractionated stereotactic radiotherapy as salvage therapy for persistent or recurrent malignant glioma

PURPOSE

A phase I dose escalation of hypofractionated stereotactic radiotherapy (H-SRT) in recurrent or persistent malignant gliomas as a means of increasing the biologically effective dose and decreasing the high rate of reoperation due to toxicity associated with single-fraction stereotactic radiosurgery (SRS) and brachytherapy.

MATERIALS AND METHODS

From November 1994 to September 1996, 25 lesions in 20 patients with clinical and/or imaging evidence of malignant glioma persistence or recurrence received salvage H-SRT. Nineteen patients at the time of initial diagnosis had glioblastoma multiforme (GBM) and one patient had an anaplastic astrocytoma. All of these patients with tumor persistence or recurrence had received initial fractionated radiation therapy (RT) with a mean and median dose of 60 Gy (44.0-72.0 Gy). The median time from completion of initial RT to H-SRT was 3.1 months (0.7-45.5 months). Salvage H-SRT was delivered using daily 3.0-3.5 Gy fractions (fxs). Three different total dose levels were sequentially evaluated: 24.0 Gy/3.0 Gy fxs (five lesions), 30.0 Gy/3.0 Gy fxs (10 lesions), and 35.0 Gy/3.5 Gy fxs (nine lesions). Median treated tumor volume measured 12.66 cc (0.89-47.5 cc). The median ratio of prescription volume to tumor volume was 2.8 (1.4-5.0). Toxicity was judged by RTOG criteria. Response was determined by clinical neurologic improvement, a decrease in steroid dose without clinical deterioration, and/or radiologic imaging.

RESULTS

No grade 3 toxicities were observed and no reoperation due to toxicity was required. At the time of analysis, 13 of 20 patients had died. The median survival time from the completion of H-SRT is 10.5 months with a 1-year survival rate of 20%. Neurological improvement was found in 45% of patients. Decreased steroid requirements occurred in 60% of patients. Minor imaging response was noted in 22% of patients. Using Fisher's exact test, response of any kind correlated strongly to total dose (p = 0.0056). None of six lesions treated with 21 Gy or 24 Gy responded, whereas there was a 79% response rate among the 19 lesions treated with 30 or 35 Gy. Tumor volumes < or =20 cc were associated with a higher likelihood of response (p = 0.053).

CONCLUSIONS

H-SRT used in this cohort of previously irradiated patients with malignant glioma was not associated with the need for reoperation due to toxicity or grade 3 toxicity. This low toxicity profile and encouraging H-SRT dose-related response outcome justifies further evaluation and dose escalation.

Atypical and malignant meningiomas: an outcome report of seventeen cases

Limited data are available concerning the outcome of patients with atypical and malignant meningiomas. We therefore analyzed the outcome of seventeen patients with meningiomas (9 atypical; 8 malignant) at Thomas Jefferson University Hospital between 1973 and 1996. Strict adherence to the 1993 WHO criteria for the typing of CNS tumors was maintained. The median potential follow-up period for all patients was 87 months. The age at diagnosis ranged from 22 to 72 (mean 51.8 years). There were 5 males and 12 females. The mean tumor diameter was 4.45 cm. Of the 16 cases where the extent of surgical resection was known, 4 were partial and 12 were complete resections. Six patients (35%) had dural or cortical invasion by tumor. Fifteen patients received postoperative megavoltage photon irradiation (mean 61 Gy). One of these fifteen pts. received an additional 20 Gy with Au-198 implantation and 1 received post-radiation chemotherapy for recurrent disease. The overall survival rate for all patients at 5 and 10 years were 87% and 58% respectively. The 5- and 10-year survival rates for atypical meningiomas were 87% and 58%; for malignant meningiomas the survival rates were 60% and 60% respectively. Five patients (30%) have died. Three of these 5 patients initially received less than 54 Gy to the tumor bed and have died of recurrent disease. Local disease progression was documented in 11 patients (65%) after surgery and in 3 patients (18%) after radiation. There was an improvement in performance status in 3 (18%) patients with a decline and no change seen in 1 (6%) and 13 (77%) respectively after receiving radiation. There appeared to be no difference in survival in patients as a function of dural or cortical invasion. Long term survival is possible for patients with atypical and malignant meningiomas treated with surgery and post-operative radiation. We are unable to distinguish a difference in outcome between these two pathological entities. Dural and cortical invasion were not associated with a decrease in survival. In addition, improved tumor control and survival may be associated with increased radiation dose.

Patterns of tumor progression after radiotherapy for low-grade gliomas: analysis from the computed tomography/magnetic resonance imaging era

Postoperative radiotherapy for low-grade gliomas has been shown in retrospective series to improve survival, compared with surgery alone. To determine the proper radiotherapy treatment volume and dose, an understanding of the patterns of failure with current radiotherapy techniques is necessary. We studied 30 consecutive patients who had a pathologic diagnosis of low-grade nonpilocytic glioma treated in our department between 1975 and 1994. Before radiotherapy, 5 patients underwent biopsy, 22 had subtotal resection, and 3 had gross total excision. All had pre- and posttreatment computed tomographic (CT) or magnetic resonance imaging (MRI) scanning. Megavoltage radiotherapy was delivered to shrinking partial (22 patients) or whole-brain (8 patients) fields. Median dose was 59.4 Gy (range, 46.4-64 Gy) in 1.8- to 2-Gy fractions. Median follow-up was 44 months (3-215 months) for the cohort and 105 months for survivors. For the entire series, 5-year overall survival and relapse-free survival rates were 50% and 41%, respectively. Sixteen patients (53%) progressed at a median of 30 months. At the time of failure, 71% (5 of 7) of pathologically evaluated tumors were of high grade. Recurrence originated within the field in all patients. Higher 5-year overall survival and relapse-free survival rates were associated (p < 0.001) with preradiotherapy functional status 1 versus functional status 2 through 4 (60% vs. 0% and 55% vs. 0%, respectively). Seizure as initial presentation was favorable over other symptoms (5-year overall survival, 64% versus 14%; p = 0.057). We conclude that 1) low-grade nonpilocytic gliomas can transform to high-grade lesions after treatment with conventional radiotherapy, 2) recurrence uniformly occurs within the treatment volume, and 3) pretreatment functional status correlates prognostically with survival. The local pattern of failure suggests that radiotherapy dose escalation within conformal fields could improve results.

Issues in nonoperative management of locally advanced non-small-cell lung cancer

The challenge for oncologists treating patients with stage III non-small-cell lung cancer (NSCLC) is to optimize a treatment strategy using nonsurgical therapies. The recognition that chemotherapy response rates for patients with previously untreated locally advanced NSCLC are higher than for those with metastatic tumors led to the testing of induction chemotherapy prior to thoracic radiotherapy. The regimen of induction vinblastine and cisplatin followed by standard thoracic radiotherapy is considered by many to be the optimal regimen against which future nonsurgical approaches should be tested. In a trial conducted by the European Organization for the Research and Treatment of Cancer, a significant survival advantage favored daily low-dose cisplatin/radiotherapy and weekly cisplatin/radiotherapy over radiotherapy alone. Presumably, the simultaneous delivery of low-dose cisplatin with radiotherapy enhanced local tumor response, and the use of higher drug doses in the induction regimens deterred the progression of micrometastatic disease. The principal disadvantage of concomitant therapy is the enhancement of normal tissue toxicity, both hematologic and esophageal, resulting in unnecessary patient morbidity and attenuation of radiotherapy and/or chemotherapy delivery. The current phase III Radiation Treatment Oncology Group trial seeks to determine the risk/benefit ratio of concurrent versus sequential delivery of chemoradiotherapy as well as the additional value of oral etoposide in this multimodality regimen. Accrual will be completed in 1998. There is also increasing interest in interdigitating systemic agents that have been established to be more active in metastatic NSCLC than cisplatin/etoposide with thoracic radiotherapy for stage III disease. Phase I/II trials using agents like carboplatin and paclitaxel with thoracic radiotherapy are summarized, as are plans for phase III testing.

Prostate imaging may not be necessary in nonpalpable carcinoma of the prostate

OBJECTIVES

Stage T1c carcinoma of the prostate is defined as a nonpalpable carcinoma (NPC-P) that is not visible by imaging and is identified by needle biopsy performed because of elevated prostate-specific antigen (PSA) concentrations. The purpose of this study was to define the incidence of normal findings on transrectal ultrasound (TRUS) and/or endorectal coil magnetic resonance imaging (EMRI) among patients with NPC-P, as well as to investigate the value of differentiating patients with Stage T1c disease from all other patients with NPC-P.

METHODS

The records of 2211 patients diagnosed with prostate carcinoma between 1988 and 1995 were reviewed to identify 291 men with NPC-P. TRUS and EMRI reports were analyzed with regard to the presence and laterality of hypoechoic nodules or low-signal areas reported on T2-weighted images, respectively. Ninety percent of patients (n = 262) had at least six prostate biopsies, 185 patients (64%) underwent both TRUS and EMRI, 224 (77%) had TRUS, and 251 (86%) had an EMRI study.

RESULTS

Results were considered normal in 101 (47%) of 214 patients undergoing TRUS, in 58 (23%) of 249 undergoing EMRI, and in 22 (12%) of 185 undergoing both TRUS and EMRI. For the side of the prostate with positive biopsy results, correlation with imaging abnormalities was better for EMRI than for TRUS (39% versus 24%). There was no significant difference in mean PSA value, distribution of Gleason score, or unilateral versus bilateral positive biopsy results among patients with normal versus abnormal findings on both TRUS and EMRI.

CONCLUSIONS

(1) Only 12% of men with NPC-P have no TRUS or EMRI abnormalities, fulfilling the criteria for Stage T1c prostate carcinoma. (2) Those patients with Stage T1c disease do not differ from patients with NPC-P up-staged by TRUS or EMRI, with regard to pretreatment PSA levels, Gleason scores, and the probability of having bilateral rather than unilateral positive biopsy results. (3) The value of classifying patients with NPC-P into Stage T1c versus higher stages of prostate carcinoma on the basis of imaging should be questioned.

Final report of a phase I/II trial of hyperfractionated and accelerated hyperfractionated radiation therapy with carmustine for adults with supratentorial malignant gliomas. Radiation Therapy Oncology Group Study 83-02

BACKGROUND

Efforts to improve local control and survival by increasing the dose of once-daily radiation therapy beyond 70 Gray (Gy) for patients with malignant gliomas has yet been unsuccessful. Hyperfractionated radiation therapy (HF) should allow for delivery of a higher total dose without increasing normal tissue late effects, whereas accelerated hyperfractionated radiation therapy (AHF) may minimize tumor repopulation by shortening overall treatment time. The Radiation Therapy Oncology Group (RTOG) conducted a randomized Phase I/II study of escalating doses of HF and AHF either carmustine (bis-chlorethyl nitrosourea [BCNU]) fro adults with supratentorial glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA). Primary study endpoints were overall survival and acute and chronic treatment-related toxicity.

METHODS

From 1983 to 1989, 786 patients with supratentorial gliomas (81% with GBM and 19% with AA) were stratified by histology, age, and performance status and randomized to receive partial brain irradiation, utilizing either HF (1.2 Gy twice daily to doses of 64.8, 72, 76.8, or 81.6 Gy) of AHF (1.6 Gy twice daily to doses of 48 or 54.4 Gy). All patients received carmustine. The distinction of pronistic factors was similar on all arms.

RESULTS

There were 747 eligible and analyzable patients among 786 enrolled patients (95%). Two patients had a Grade 5 and 65 patients had a Grade 4 chemotherapy toxicity. Two patients in the 81.6 Gy arm experienced late Grade 4 radiation toxicity and there was 1 late radiation-associated death in the 54.4 Gy arm. The rate of Grade 3 of worse radiation toxicity at 5 years, calculated by the delivered does level, was 3% in the lowest total dose arms (48 and 54.4 Gy), 4% in the intermediate dose arms (64.8 and 72 Gy), and 5% in the highest dose arms (76.8 and 81.6 Gy) (p = 0.54). Survival rates at 2 and 5 years were: 21% and 11%, and 4%, respectively, for GBM patients. There were no significant differences between the treatment arms with regard to median survival time (MST), when analyzed by the originally assigned dose. The MST for all patients varied between 10.8 months and 12.7 months (P = 0.59); between 9.6 months and 11 months for patients with GBM (P = 0.43); and between 30.4 months and 85.8 months for patients with AA (P = 0.78). Analysis of the survival rates for all patients by dose received rather than by dose assigned revealed a 14% 5-year survival rate for the lower HF doses (64.8 and 73 Gy), 11% for the higher doses (76.8 and 81.6 Gy), and 10% for the AHF doses (48 and 54.4 Gy) (P = 0.1). The subgroup a AA patients had a better MST (49.9 months) in the lower received HF doses than in the higher HF doses (34.6 months) (P = 0.35). In contrast, GM patients who received the higher HF doses had survival superior to the patients in the AHF arms (MST of 11.6 months and 10.2 months, respectively, P = 0.04).

CONCLUSIONS

The use of HF with BCNU and dose escalation up to 81.6 Gy is both feasible and tolerable, although late toxicity increases slightly with increasing dose. The best MST with the least toxicity were observed for AA in the lower received HF doses (72 and 64.8 Gy). Accordingly, 72 Gy in two 1.2 Gy fractions was used as the investigational arm of a completed Phase III trial (RTOG 90-06). In contrast, for GBM patients, longer survival times were noted in the higher received HF doses (78.6 and 81.6 Gy), suggesting the role for further dose escalation. The low toxicity rate with AHF arms suggest that further dose escalation is possible and is currently occurring in RTOG 94-11.

Characteristics of a dedicated linear accelerator-based stereotactic radiosurgery-radiotherapy unit

A stereotactic radiosurgery and radiotherapy (SRS/SRT) system on a dedicated Varian Clinac-600SR linear accelerator with Brown-Roberts-Wells and Gill-Thomas-Cosman relocatable frames along with the Radionics (RSA) planning system is evaluated. The Clinac-600SR has a single 6-MV beam with the same beam characteristics as that of the mother unit, the Clinac-600C. The primary collimator is a fixed cone projecting to a 10-cm diameter at isocenter. The secondary collimator is a heavily shielded cylindrical collimator attached to the face plate of the primary collimator. The tertiary collimation consists of the actual treatment cones. The cone sizes vary from 12.5 to 40.0 mm diameter. The mechanical stability of the entire system was verified. The variations in isocenter position with table, gantry, and collimator rotation were found to be < 0.5 mm with a compounded accuracy of < or = 1.0 mm. The radiation leakage under the cones was < 1% measured at a depth of 5 cm in a phantom. The beam profiles of all cones in the x and y directions were within +/- 0.5 mm and match with the physical size of the cone. The dosimetric data such as tissue maximum ratio, off-axis ratio, and cone factor were taken using film, diamond detector, and ion chambers. The mechanical and dosimetric characteristics including dose linearity of this unit are presented and found to be suitable for SRS/SRT. The difficulty in absolute dose measurement for small cone is discussed.

Prognostic factors for local and distant recurrence in stage I and II cervical carcinoma

PURPOSE

The effects of tumor size, parametrial involvement, and other variables on treatment outcome for patients with Federation Internationale de Gynecologie et d'Obstetrique (FIGO) Stage I or II cervical carcinoma, as well as treatment complications, were analyzed retrospectively.

METHODS AND MATERIALS

Records of 125 patients with FIGO Stage I or II carcinoma of the uterine cervix selected for curative radiotherapy between January 1980 and December 1990 were reviewed. Twelve patients (9.9%) underwent adjuvant extrafascial hysterectomy and 8 patients (6.4%) received chemotherapy. Median age was 55 years. Median follow-up time was 40 months, and minimum follow-up time was 24 months. The data were analyzed for site of first relapse, survival, overall incidence of complications, and incidence of grade 4 complications.

RESULTS

The overall 5-year survival was: Stage IA: 100%, Stage IB: 72%, Stage IIA: 90%, and Stage IIB: 72%. The 5-year survival with no evidence of disease (NED) was: Stage IA: 100%, Stage IB: 67%, Stage IIA: 90%, and Stage IIB: 50%. Patients with bulky (> 5 cm) tumors had a shorter overall and NED survival than patients with nonbulky tumors (53% vs. 83%; p = 0.0008 and 44% vs. 78%; p = 0.0001, respectively). Thirty-nine tumor recurrences (39 out of 125 = 31%) occurred and were scored as local (23 out of 125 = 18.3%), if initial failure had a local component, or distant (16 out of 125 = 12.7%), if initial failure was distant only. Patients with bulky (more than 5 cm) tumors (32 out of 125) were more likely to experience a recurrence (18 out of 32 = 56%) than patients with nonbulky tumors (21 out of 93 = 22%; p = 0.0004). The initial site of recurrence was more likely to be local for bulky tumors (14 out of 18 = 78%) than for nonbulky tumors (9 out of 21 = 43%; p = 0.03). The probability of a recurrence increased with the number of involved parametria (none: 20 out of 78 = 25%; one: 12 out of 34 = 35%; two: 7 out of 13 = 54%; p = 0.04 for linear trend), as did the probability that the initial failure was distant rather than local (none: 4 out of 20 = 20%; one: 7 out of 12 = 58%; two: 5 out of 7 = 71%; p = 0.01 for linear trend). Positive lymph nodes, vessel invasion, and low hemoglobin level all correlated with an increased risk of a recurrence (RR 2.41, p = 0.004; RR 2.20, p = 0.01; OR 2.02, p = 0.01, respectively). There were 46 complications among 37 (29%) patients. The incidence of grade 4 complications was 8.8% (11 out of 125). History of pelvic surgery and bulky tumor were significant predictors of a grade 4 complication (p < 0.0001 and 0.021, respectively). Also, a dose rate to point A of > 0.6 Gy/h increased the chance of a grade 4 complication (p = 0.007).

CONCLUSION

For patients with FIGO Stage I or II cervical carcinoma, tumor size was more predictive of local recurrence than was overall stage, and the extent of parametrial involvement was strongly predictive of distant recurrence, as was the stage. These findings suggest that tumor size and extent of parametrial involvement should be incorporated into the staging system. Patients with bulky tumors had a shorter survival and were more likely to experience a grade 4 toxicity of therapy. Dose rate to point A of > 0.6 Gy/h was associated with the increased risk of grade 4 complications.

Increased risk of second malignant neoplasms outside radiation fields in patients with cervical carcinoma

BACKGROUND

The relative risk of second primary cancers was evaluated in 125 women with International Federation of Gynecology and Obstetrics (FIGO) Stages I and II cervical carcinoma treated radically with radiation therapy between January 1980 and December 1990.

METHODS

Medical records of patients were reviewed to evaluate the incidence of second malignant neoplasms. Only tumors histologically proven were scored. The annual 5-year age-specific cancer incidence data per 100,000 white women in the years 1981-1985 were obtained from the National Cancer Institute's Surveillance, Epidemiology and End Results database. The relative risks were calculated as the ratio of observed-to-expected numbers of second cancers, using person-years at risk accumulated for each individual in the study.

RESULTS

During the follow-up time (through December 1992), 10 women whose median age was 65.5 years at the time cervical cancer was diagnosed were found to have 11 second primary cancers. Nine of these cancers were metachronous with regard to cervical cancer and included breast (4), lung (2), myeloma (1), non-Hodgkin's lymphoma (1) and vulva(1). The metachronous tumors were diagnosed at a median age of 74 years and at median follow-up time of 34 months. Two of the cancers were synchronous with cervical cancer and included bladder (1) and thyroid (1). All of the second tumors were located outside radiation fields. None of the patients with second tumors received chemotherapy during treatment for cervical carcinoma. The relative risk of developing a second cancer of any type was 2.31 (95% confidence interval [CI] = 1.15-4.13), whereas the relative risk of developing a metachronous breast cancer was 2.64 (95% CI = 0.72-6.75).

CONCLUSIONS

An increased risk of second primary cancers developing was observed among 125 patients with FIGO Stages I and II cervical carcinoma, which may suggest an abnormal genetic background and/or a common etiology for the initial and second tumors. The increased risk of breast cancer occurring as a second primary is in contrast with previously published studies reporting a decreased risk of breast cancer in survivors of cervical cancer.

Preservation of cranial nerve function after treatment of acoustic neurinomas with fractionated stereotactic radiotherapy. Preliminary observations in 26 patients

Twenty-seven acoustic tumors in 26 patients were treated with multiple fractionated linear-accelerator-based stereotactic radiotherapy (SRT). All patients with intact pretreatment facial nerve function with either small or large tumor volumes have thus far experienced no treatment-related facial neuropathy, including 9 patients with a mean follow-up of 22.4 +/- 1.6 months. The incidence of evaluable trigeminal neuropathy was 13%, and in 5 of 7 patients with serviceable pretreatment hearing, audiometry was unchanged in the immediate posttreatment period. Longer follow-up will be necessary to evaluate hearing preservation after SRT. Tumor response with central necrosis was seen in all assessable patients. SRT can be performed for cerebellopontine angle tumors with accuracy and reproducibility. It achieves a biological response similar to single fraction radiosurgery and may lower the incidence of facial and trigeminal neuropathies.

Endogeneous interferon alpha/beta produced by murine Kupffer cells augments liver-associated natural killing activity

Nonparenchymal liver cells from untreated C3HeB/FeJ mice, when incubated in medium containing-10% fetal bovine serum or portal serum, produced significant amounts of interferon alpha/beta (IFN alpha/beta). In contrast, other cell populations (spleen, mononuclear blood cells and peritoneal cells) from C3HeB/FeJ mice or nonparenchymal liver cells from other strains of mice (C3H/HeJ, germ-free C3H/HeN and C57Bl/6J) produced little or no detectable IFN in fetal bovine serum under the same culture conditions. The cells in the nonparenchymal liver cell population responsible for IFN alpha/beta production were adherent, phagocytic, silica-sensitive, carbonyl-iron-sensitive, and Thy1.2-, presumably Kupffer cells or resident liver macrophages. IFN alpha/beta production by cultured Kupffer cells was not observed if medium containing fetal bovine serum or portal serum was treated with polymyxin B or if Kupffer cells were cultured in serum-free medium. This suggested that small amounts of endotoxin in fetal bovine or portal serum stimulated Kupffer cells to produce IFN alpha/beta. Possibly, Kupffer cells are in a different state of activation/maturation than peritoneal and splenic macrophages since the sensitivity of resident Kupffer cells from C3HeB/FeJ mice to the stimulatory effects of endotoxin. The endogenous production of IFN alpha/beta by Kupffer cells from C3HeB/FeJ mice can augment liver-associated natural killer (NK) activity against YAC-1 cells (4h) and induce liver-associated cytotoxic activity, not restricted by the major histocompatibility complex, against NK resistant P815 mastocytoma cells (18 h).

Natural antitumor defense system of the murine liver

Murine nonparenchymal liver cells from various genetic strains isolated by collagenase digestion and differential sedimentation contain both lymphocytes and macrophages. Nonparenchymal liver cells as well as spleen cells, mononuclear blood cells, and peritoneal exudate cells from C3HeB/FeJ mice were tested for natural cytotoxicity against YAC-1 (sensitive to NK cells) and P815 (resistant to NK cells) tumor cell lines. Resident peritoneal exudate cells exerted no cytotoxicity against either tumor cell, whereas spleen and mononuclear blood cells lysed only YAC-1. In contrast, nonparenchymal liver cells lysed both YAC-1(4 h) and P815 (18 h) tumor cells. Treatment of nonparenchymal liver cells with anti-asialo GM1 and complement abolished the antitumor activity against both tumor cell lines but not the phagocytic activity. Nonadherent nonparenchymal liver cells exerted greater cytotoxicity against YAC-1 tumor cells but little cytotoxicity against P815 tumor cells when compared with unfractionated cells. Adherent nonparenchymal liver cells (macrophages) from untreated mice exerted no antitumor activity against either tumor cell. In contrast, adherent nonparenchymal liver cells from Corynebacerium parvum treated mice were directly cytotoxic to P815 tumor cells. Spleen cells that are normally not cytotoxic to P815 tumor cells (18 h) became cytotoxic when mixed with adherent nonparenchymal liver cells from untreated mice. These results indicate that the tumoricidal effector cell in nonparenchymal liver cells from untreated mice appears to be the NK cell. Apparently, murine liver macrophages from untreated mice do not have tumoricidal activity per se but can "activate" NK cells to kill tumor cells normally resistant to NK cells.